FIG. 1 shows a prior art semiconductor light emitting device. The reference numeral 1 designates a semiconductor light emitting element which is constituted by epitaxial growth layers comprising a p type indium-phosphorus (hereinafter referred to as "p-InP") semiconductor substrate 2, a p-InP buffer layer 3, a p type indium-gallium-arsenic-phosphorus (hereinafter referred to as "p-InGaAsP") semiconductor clad layer 4, a p-InGaAsP active layer 5, an n-InGaAsP clad layer 6, an n type indium-gallium-arsenic (hereinafter referred to as "n-InGaAs") semiconductor contact layer 7, an insulating layer 8 such as silicon dioxide (SiO.sub.2), and electrodes 9 and 10. In such a semiconductor element 1, a light emitting region 11 which conducts a light emission is produced at the center portion of the active layer 5. The reference numeral 12 designates a sphere lens for collecting the light from the semiconductor light emitting element 1. The reference numeral 13 designates an adhesive for fixing the sphere lens 12 onto the semiconductor light emitting element 1.
In this prior art semiconductor light emitting device with such a construction when a current is injected thereinto from the electrodes 9 and 10 light is isotropically radiated from the light emitting region 11 of the active layer 5, and it is guided to the outside, collected by the sphere lens 12 attached to the substrate 2. In this semiconductor light emitting device the conductivity types of the substrate 2 and the epitaxial layers 3 to 7 and the energy band gap thereof are selected such that a current is concentrated on the light emission region 11, that the recombinations of the electron hole pairs occur thereat concentrately, and that the light generated at the regions from the light emitting region 11 to the sphere lens 12 can sufficiently penetrate those layers.
In this prior art semiconductor light emitting device, however, there is a problem that a skill is required for fixing the sphere lens 12 onto the substrate 2 by the adhesive 13 without soiling the portions other than the required portion by the adhesive 13.